I need to be able to add the sum of a column of data into the cell at the
bottom of the column. I can do this using

ActiveCell.FormulaR1C1 = "=SUM(R[-121)]C:R[-1]C)"


However this number of rows in the column may vary so I cannot use a
pre-defined R1C1 range in the formula. Each time the code is run the number
of rows may be more or less so the -121 will vary.

How can I overcome this please?